The new lichen species Lecidea phaeophysata is described from rocks close to the coast in Italy, Portugal, France and Ireland. Distinguishing features include Porpidia-type asci and simple paraphyses that are fuscous brown pigmented in their upper section. Its systematic position is discussed but is unclear as molecular data are lacking (all collections are c. 20 years old). Therefore, we chose to describe the species in a broadly-circumscribed Lecidea rather than erecting a new monotypic genus. A key to saxicolous lecideoid lichens present on Atlantic coasts in Europe is also provided.

Staurothele nemorum is described as new to science from the southern Great Plains of central North America. The species is characterized by a thin, areolate, epilithic thallus, sessile perithecia, globose to oblong hymenial algal cells and 8-spored asci. Staurothele hymenogonia is restored to the North American flora, based on material from the south-western Great Plains. An updated key to North American members of Staurothele s. lat. is provided.

Opegrapha multipuncta and Schismatomma quercicola are two sterile European lichens reproducing only vegetatively by means of soredia. RAxML and Bayesian analyses of newly generated sequence data from the mitochondrial ribosomal RNA small subunit provide clear evidence that these two species do not belong to the Arthoniomycetes, but to the Lecanoromycetes. In our phylogenetic analyses, O. multipuncta is nested in the genus Porina (Porinaceae) as sister to P. austroatlantica, while S. quercicola is nested in the genus Schizotrema (Graphidaceae) as sister to S. zebrinum. The following new combinations are introduced: Porina multipuncta (Coppins & P. James) Ertz, Coppins & Frisch and Schizotrema quercicola (Coppins & P. James) Ertz, Frisch & Sanderson. Schizotrema quercicola represents the first record of the genus Schizotrema for Europe and the first sorediate member in this genus. The species is newly recorded from Norway. The lichenicolous habit of Arthonia invadens is confirmed.

Cryptolechia carneolutea is the type species of the genus Cryptolechia, a rare taxon classified as endangered in the UK, now largely confined to ancient Fraxinus trees. The only tree with abundant growth of the species in one of its strongholds, the Slapton Ley National Nature Reserve in Devon, was blown over in a storm in April 2017, making it possible to collect material for molecular studies and transplant specimens to other Fraxinus trees in the area. The results of the phylogenetic analysis revealed C. carneolutea to be nested within the genus Gyalecta (Gyalectaceae). This further supports a broad circumscription of Gyalecta, after also including species previously placed in Belonia and Pachyphiale as proposed in other recent studies. It might be possible to introduce an alternative genus concept in Gyalectaceae, not schematically based on ascoma type and ascospore number, but presently not enough data are available to proceed with such a novel classification. A review of the taxonomic concept of Cryptolechia demonstrates that this name was used inconsistently in the past, and its possible inclusion in Gyalecta was anticipated by other authors. As the majority of species presently classified in Cryptolechia had been placed in Gyalecta before, only five new combinations are required to provide formal inclusion of all taxa in the latter genus: Gyalecta bicellulata (Kalb) D. Hawksw. & Lücking comb. nov., G. caudata (Kalb) D. Hawksw. & Lücking comb. nov., G. pittieriana (Kalb et al.) D. Hawksw. & Lücking comb. nov., G. saxatilis (Vězda) D. Hawksw. & Lücking comb. nov. and G. stellaris (Müll. Arg.) D. Hawksw. & Lücking comb. nov. We also supersede the previous lectotypification of Parmelia carneolutea Turner with the discovery of the holotype specimen in BM.

Three species, Lobothallia brachyloba Paukov & I. V. Frolov, L. epiadelpha Paukov & A. Nordin and L. zogtii Paukov & Davydov, from arid regions of Eurasia (Russia, Kazakhstan, Kyrgyzstan, China and Mongolia) are described as new to science. Lobothallia brachyloba has flat, firmly attached lobes, immersed apothecia lacking a distinct thalline margin, and contains norstictic acid. Both Lobothallia epiadelpha and L. zogtii contain stictic acid and have a brown thallus and sessile apothecia. Lobothallia epiadelpha initially develops on crustose Circinaria spp, has thick lobes loosely attached to the substratum, and brown apothecial discs with constant thalline margins. Lobothallia zogtii is a free-living species with brownish black to jet black apothecial discs surrounded by a receding thalline margin. Lecanora bogdoënsis is synonymized with Lobothallia praeradiosa and Lobothallia helanensis is synonymized with L. subdiffracta. Three new combinations, Lobothallia hedinii (H. Magn.) Paukov, A. Nordin & Sohrabi, L. lacteola (Oxner) Şenkardeşler, Paukov, Davydov & Sohrabi, and L. subdiffracta (H. Magn.) Paukov, are proposed. Phylogenetic analyses of Lobothallia brachyloba, L. epiadelpha and L. subdiffracta (ITS, mtSSU) are presented, showing their relationships within Lobothallia. The lectotype of the name Aspicilia lacteola Oxner is designated. A key to 18 species of Lobothallia is provided.

Five species of Eremothecella are recorded from the Andaman Islands, two of which are described as new: Eremothecella ajaysinghii Jagad. Ram & G. P. Sinha and E. nicobarica Jagad. Ram & G. P. Sinha. Eremothecella ajaysinghii has whitish grey, pruinose ascomata and 8–10(–11)-septate ascospores, while E. nicobarica has non-pruinose ascomata and (14–)15–17-septate ascospores. Eremothecella calamicola Syd., E. macrosperma (Zahlbr.) Sérus. and E. variratae (Aptroot & Sipman) Sérus. are reported as new records for India. An updated worldwide key to species of the genus is presented.

The Umbilicaria polyphylla aggregate (U. polyphylla (L.) Baumg., U. subpolyphylla Oxner and U. iberica Sancho & Krzewicka) is discussed based on morphological, chemical and molecular data. Umbilicaria iberica is proposed to be a later synonym of U. subpolyphylla. The constructed nrITS + mtLSU phylogeny, which includes specimens with wide geographical ranges, shows that both U. polyphylla and U. subpolyphylla are monophyletic and closely related. Both species have the same type of thalloconidia and identical secondary metabolites. Umbilicaria subpolyphylla has prominent phenotypic differences when compared to U. polyphylla including the monophyllous thallus with a dull upper surface and an elevated, slightly wrinkled centre, often covered with white pruina, and a medulla of the ‘U. havaasii’ type. Phylogenetic evidence for the bipolar distribution of both U. polyphylla and U. subpolyphylla is provided. Sympatric speciation in one region followed by long-distance dispersal seems to be the most plausible phylogeographical explanation for the observed patterns. Umbilicaria subpolyphylla is found in southern temperate-subtropical (Mediterranean) mountains, at least in Europe.

The Parmelia saxatilis aggregate is comprised of three species in Europe, proposed to differ in morphological, distributional or chemical characters. In this study, we sampled nearly 200 thalli from five sites across a steep ecological gradient in Scotland to investigate the distribution of the species in the aggregate, and we characterized all specimens by morphological, chemical and ITS sequence variation. In our sample, 191 specimens were identified to species using ITS. We confirm that a PCR length assay can be used for separation of P. saxatilis s. str. from P. ernstiae and P. serrana because across our sample, P. saxatilis s. str. consistently includes a group I intron c. 200 bp. Using sequences for specimen identification, we test previously proposed characters to diagnose specimens and use multivariate analysis to identify the most consistent features which may be used for identification among species. First, we test lobe morphology, presence and amount of pruina, distribution of isidia, lobe tip colour, and chemistry. Second, we use classification trees that quantify the contributions of 1) morphological and chemical factors, and 2) morphological and ecological factors, to a priori ITS-barcoded specimens. Parmelia saxatilis s. str., P. ernstiae and P. serrana all occur across the sampled gradient but differ in the frequency of occurrence, with P. saxatilis s. str. more frequent in the relatively drier east, and P. ernstiae more frequent in the wetter west. Parmelia serrana was collected around a third as often as the other two species, but more frequently on tree branches than expected. For all the morphological characters examined, all the species show some overlap and no morphological features are diagnostic, though trends are apparent by species. The classification tree approach holds promise for discovering the most meaningful variation for field workers to approach correct identifications. Chemical variation using TLC is perhaps the best way to distinguish most specimens but, even here, overlap in chemosyndromes exists among the species.

Arctoparmelia collatolica is described as a species new to science based on morphological, chemical and molecular data. The species is similar to the usnic acid-deficient chemotype of A. centrifuga but differs in the grey-brown to brown upper surface in the central part of the thallus and ivory white to pale brown rhizines. The species contains collatolic acid and its derivatives. Seven secondary lichen substances are reported as new for the genus Arctoparmelia. A key to Arctoparmelia taxa is provided.

In this study we clarify the phylogeny and reassess the current taxonomy of the Micarea prasina group, focusing especially on the M. byssacea and M. micrococca complexes. The phylogeny was investigated using ITS, mtSSU and Mcm7 regions from 25 taxa belonging to the M. prasina group. A total of 107 new sequences were generated. Data were analyzed using maximum parsimony and maximum likelihood methods. The results reveal five undescribed well-supported lineages. Four of the lineages represent new species described as Micarea pseudomicrococca Launis & Myllys sp. nov., M. czarnotae Launis, van den Boom, Sérusiaux & Myllys sp. nov., M. microareolata Launis, Pykälä & Myllys sp. nov. and M. laeta Launis & Myllys sp. nov. In addition, a fifth lineage was revealed that requires further study. Micarea pseudomicrococca is characterized by an olive green granular thallus, small cream-white or brownish apothecia lacking the Sedifolia-grey pigment and two types of paraphyses up to 2 µm wide. Micarea czarnotae forms a granular, densely granular or continuous olive green thallus, convex to hemispherical apothecia often with the Sedifolia-grey pigment and no crystalline granules in the thallus. Micarea microareolata is characterized by a ± pale green areolate thallus (composed of goniocysts), cream-white apothecia lacking the Sedifolia-grey pigment and narrow spores. Micarea laeta has a vivid to olive green granular thallus, pale apothecia lacking the Sedifolia-grey pigment and wider spores compared to M. microareolata. Descriptions, images and a key are provided for the new species. Crystalline granules are introduced as a novel species-level character for Micarea.

The new species Psoroma nivale is described from an area of late snow-lie in the Keglo Bay area on the eastern side of Ungava Bay, northern Québec, Canada. It is superficially similar to P. hypnorum but has a dark, brownish black thallus colour without reddish hues, much-branched, proliferating squamules, thick paraphyses, distinct but inconspicuous IKI+ ascus tube structures, and characteristic elongate, bacilliform, often asymmetrical ascospores. The new species is compared with possible related taxa and its systematic position discussed. A key to the species of pannarioid lichens reported from arctic areas of North America is also provided.

We provide an updated survey for Sri Lanka of species of Graphis sensu Staiger, recently divided into Graphis s. str. and Allographa, including brief descriptions and a key to all 124 species currently known. Six new species are described: Allographa bambusicola Weerakoon, Lücking & Aptroot, a bambusicolous Allographa with entire labia, a laterally carbonized excipulum, 80–100 × 15–17 µm large, muriform ascospores and a rather thick, irregularly verrucose lateral thalline margin of the lirellae; A. weerasooriyana Weerakoon, Arachchige & Lücking, a corticolous Allographa resembling A. rustica Kremp. in overall anatomy and chemistry, but with a verrucose thalline margin of the lirellae and labia not distinctly raised above the thalline margin; Graphis flosculifera Weerakoon, Lücking & Aptroot, a corticolous Graphis resembling G. insulana but differing in the unique disposition of the lirellae and the slightly more elongate ascospores; G. rajapakshana Weerakoon, Lücking & Aptroot, a corticolous Graphis resembling G. desquamescens, including in ascospore size, but with lirellae with a distinct lateral thalline margin; G. rimosothallina Weerakoon, Lücking & Aptroot, a corticolous Graphis with a thick, uneven, rimose thallus and Fissurina-like lirellae, a completely carbonized excipulum and transversely 7-septate ascospores, 32–37 × 8–10 µm; and G. thunsinhalayensis Weerakoon, Arachchige & Lücking, a corticolous Graphis resembling G. subalbostriata but with smaller ascospores and lacking white lines between the striae of the labia. We also validate the name G. verrucoserpens Lücking. A total of 106 species are reported here for the first time from Sri Lanka. A biogeographical comparison with two other well-sampled countries (Costa Rica and Thailand) revealed a significantly higher similarity in species composition with Costa Rica than between Thailand and Costa Rica, suggesting a potential signature of the ‘biotic ferry’ hypothesis, that is the migration of lineages from Gondwana (partly corresponding to the modern Neotropics) via the north-eastwards drifting Indian subcontinent and subsequent interchange with Laurasia (partly corresponding to the modern eastern Paleotropics). However, the evolutionary timeline of the clades involved does not support this hypothesis and suggests an alternative explanation of geologically more recent mid- to long-distance dispersal.

A new species of Chaenotheca, C. biesboschii, has been found in the freshwater tidal area of the Biesbosch in the Netherlands, a national park well known for harbouring several rare and threatened mosses and lichens. A phylogenetic analysis of the ITS region revealed some strongly supported infrageneric clades in Chaenotheca which were given informal names, and some were assigned provisional names in anticipation of generic recognition. The analysis also showed that the new species differed in the sequenced region from other European Chaenotheca species. Chaenotheca biesboschii might be mistaken for C. gracillima but, in addition to a considerable difference in the ITS region, it also differs from this species in morphology. It is also similar to C. servitii but again differs in morphology. Chaenotheca biesboschii inhabits decorticated wood in the oldest stages of forest development of abandoned willow coppices. In 2016 and 2017 a fairly large population was found in an area comprising several square kilometres. In the Biesbosch area, extensive woodlands have developed only since the 1950s and therefore C. biesboschii might have been recently established in the area, possibly following climatic warming. The new species is characterized by having an immersed, glaucous green thallus; apothecia 0·9–1·4 mm high; capitulum on the lower side when young with a ring-like thickening covered by a yellow pruina; when mature with a rusty brown pruina on the capitulum and upper part of stalk; spherical spores, 3·5–5·5 µm diam., ornamented by irregular cracks, medium brown; photobiont Stichococcus. A key to the European species of Chaenotheca is provided.

A new neotypus is designated for Thamnolia vermicularis in accordance with the protologue. The taxonomy is best reflected by molecular evidence which recognizes three subspecies: the widespread subsp. vermicularis, and the geographically more restricted subsp. taurica (in the eastern Alps) and subsp. tundrae (in the Arctic region). The nomenclatural consequences resulting from these changes require that two new combinations are made.

Species identification in the tropical lichen genus Phyllopsora is generally challenging and is based on ascospore morphology, vegetative dispersal units, thallus structure and secondary chemistry. As several type specimens are in poor condition and difficult to interpret, it is often unclear how these old names fit with the currently used taxonomy. In the present study, we aim to identify species boundaries in Phyllopsora s. str. supported by an integrative approach using multiple sources of evidence. We investigated a substantial amount of herbarium as well as freshly collected material and generated mtSSU and ITS sequence data from most of the described species, including several types. Species delimitation analyses are applied on the gene trees using mPTP and we construct a species tree of both markers with *BEAST, facilitating discussion of species delimitation and sister-relationships. Comparing morphology, chemistry and molecular data, we found that the mPTP analyses split established species repeatedly. Based on our integrative results, we exclude nine species from the genus, resurrect one (P. melanoglauca Zahlbr.), reduce two into synonymy with other Phyllopsora species and describe five as new to science: Phyllopsora amazonica Kistenich & Timdal (which shares the secondary chemistry (atranorin and terpenoid pattern) with P. halei chemotype 1, but differs, e.g., in having smaller areolae that are attached to a thinner, white prothallus, and in having more persistently marginate and less convex apothecia), Phyllopsora concinna Kistenich & Timdal (which shares the secondary chemistry (atranorin and parvifoliellin) with P. parvifoliella and P. rappiana, but differs from both in forming larger isidia, having a white prothallus, apothecial margin paler than the disc, and longer and broader ascospores), Phyllopsora furfurella Kistenich & Timdal (which is here segregated from P. furfuracea based on having a white prothallus and in containing skyrin in the hypothecium (K+ red)), Phyllopsora isidosa Kistenich & Timdal (which differs from P. byssiseda in forming a more crustose thallus with more delicate isidia, and from P. isidiotyla in forming somewhat coarser, less branched isidia) and Phyllopsora neotinica Kistenich & Timdal (a neotropical species here segregated from the now exclusively paleotropical P. chodatinica, differing in containing an unknown xanthone (not chodatin)). Lectotypes are designated for Biatora pyrrhomelaena Tuck., Lecidea leucophyllina Nyl., L. pertexta Nyl., and P. brachyspora Müll. Arg. In total, we accept 54 species in the genus Phyllopsora.

Ten new species of Trypetheliaceae are described: Astrothelium bullatothallinum from Venezuela, which is close to A. aeneum but differs by the bullate thallus with a thick cortex, intermixed in a mosaic with the prothallus; A. cayennense from French Guiana, which is similar to A. flavomegaspermum but with a yellow pigment in the pseudostroma near the ostioles; A. diaphanocorticatum from Papua New Guinea, which has a bullate thallus with a thick hyaline cortex and 3-septate ascospores of 25–28×10–12 μm; A. macroeustomum from French Guiana, with joint lateral ostioles, UV+ yellow ostiolar region and 5-septate ascospores of 50–55×12–17 μm; A. minicecidiogenum from Costa Rica, with muriform ascospores of 70–90×20–25 μm, without pseudostromata, with solitary ascomata, lateral ostioles and an inspersed hamathecium; A. palaeoexostemmatis from Thailand, which is similar to A. exostemmatis but with larger, I+ blue ascospores; A. quasimamillanum from Brazil, with muriform ascospores of 30–33×9·5–10·5 μm, without pseudostromata, with solitary ascomata, lateral ostioles and an inspersed hamathecium; A. studerae from Brazil, with astrothelioid ascomata, lichexanthone only in the pseudostromata, 3-septate ascospores of 21·5–23·0×6·5–7·5 μm; A. tanianum from Malaysia, with a bullate thallus, solitary ascomata, covered by the thallus, (9–)11(–15)-septate ascospores, 75–100×20–22 μm; and Pseudopyrenula miniflavida from Brazil, with a yellow-inspersed hamathecium, the inspersion dissolving in KOH without colour change, and 3-septate ascospores, 15–17×5·5–6·5 μm. The unusually thick, hyaline cortical layer of the thallus of Astrothelium diaphanocorticatum, through which the individual algal cells are clearly visible, is discussed. Furthermore, 30 species are reported from 34 countries in which they had previously been unrecorded; one (Astrothelium inspersaeneum) is from a new continent, Asia.

The genus Graphis sensu Staiger was recently divided into two genera, Graphis s. str. and Allographa. The latter contains mostly species with robust lirellae with a well-developed, often massively carbonized excipulum. With one exception, it also contains all species with a pigmented, yellow to orange pruina on the lirellae. Until now, seven species of Allographa were known with this character, all present in the Neotropics and one also in Africa. Here we describe two further species, both from tropical Asia, thus extending the known distribution of Allographa species with pigmented lirellae to the entire tropics. Allographa kamojangensis Jatnika, Noer & Lücking sp. nov. from Indonesia (Java) was recognized as a new taxon on the social media Facebook site Lichens Connecting People. Detailed studies showed that it deviates from the neotropical A. firferi in the much larger ascospores and the orange, K+ immediately purple-violet pigment, and from A. lutea in the completely carbonized excipulum and the larger ascospores. Allographa jayatilakana Weerakoon, Arachchige & Lücking sp. nov. was discovered in the second author's backyard during a recent inventory of Graphidaceae in Sri Lanka. It differs from A. flavominiata in the much shorter ascospores, from A. firferi in the terminally muriform ascospores, and from A. ochracea in the yellow-orange, K+ yellow then slowly purple-violet pruina. A key is presented to all nine species of Allographa with pigmented lirellae.

An identification key to the 39 species of Menegazzia recorded for Australia and its offshore islands (including Tasmania) is presented. Distribution patterns are discussed and summarized. Mainland Australia supports 19 species, with seven endemics, and shares 12 species with Tasmania, six with New Zealand and one with South America. The new species, Menegazzia williamsii Kantvilas from New South Wales, is described and is characterized by an inflated, fragile, esorediate thallus containing stictic acid but lacking isopigmentosin, 2-spored asci and an inspersed epihymenium. In addition, M. hypernota Bjerke, formerly known only from New Zealand, is recorded from Tasmania for the first time.